Study shows marijuana could alter sperm

Marijuana users in the Caribbean are rejoicing as more and more countries mull the decriminalisation of or actively in the process of decriminalising marijuana.

But as laws restricting the use of the drug are struck down, a group of researchers are advising men to hold off on using it for at least six months if they are trying to conceive.

This, as research shows that marijuana can alter a man's sperm.

The research from Duke Health suggests men in their child-bearing years should also consider how the active ingredient in marijuana, tetrahydrocannabinol (THC) could impact their sperm and possibly the children they conceive during periods when they’ve been using the drug.

a release said much like previous research that has shown tobacco smoke, pesticides, flame retardants and even obesity can alter sperm, the Duke research shows THC also affects epigenetics, triggering structural and regulatory changes in the DNA of users’ sperm.

Experiments in rats and a study with 24 men found that THC appears to target genes in two major cellular pathways and alters DNA methylation, a process essential to normal development.

The researchers do not yet know whether DNA changes triggered by THC are passed to users’ children and what effects that could have.

“What we have found is that the effects of cannabis use on males and their reproductive health are not completely null, in that there’s something about cannabis use that affects the genetic profile in sperm,” said Scott Kollins, Ph.D., professor in psychiatry and behavioral sciences at Duke and senior author of the study.

“We don’t yet know what that means, but the fact that more and more young males of child-bearing age have legal access to cannabis is something we should be thinking about,” Kollins said.

The study defined regular users as those who smoked marijuana at least weekly for the previous six months. Their sperm were compared to those who had not used marijuana in the past six months and not more than 10 times in their lifetimes.

The higher the concentration of THC in the men’s urine, the more pronounced the genetic changes to their sperm were, the authors found.

THC appeared to impact hundreds of different genes in rats and humans, but many of the genes did have something in common -- they were associated with two of the same major cellular pathways, said lead author Susan K. Murphy, Ph.D., associate professor and chief of the Division of Reproductive Sciences in obstetrics and gynecology at Duke.

The Duke team plans to continue its research with larger groups. They intend to study whether changes in sperm are reversed when men stop using marijuana. They also hope to test the umbilical cord blood of babies born to fathers with THC-altered sperm to determine what, if any epigenetic changes, are carried forward to the child.

“We know that there are effects of cannabis use on the regulatory mechanisms in sperm DNA, but we don’t know whether they can be transmitted to the next generation,” Murphy said.

“In the absence of a larger, definitive study, the best advice would be to assume these changes are going to be there,” Murphy said. “We don’t know whether they are going to be permanent. I would say, as a precaution, stop using cannabis for at least six months before trying to conceive.”

Their findings will be published online on December 19 in the journal Epigenetics.

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